In many situations, a device is required for expanding a constricted passageway of a blood vessel or the liver, or maintaining an open passageway through a vessel portion. Such situation arise, for example, when the blood does not flow smoothly or the passageways of the vessel portion are constricted due to arteriosclerosis or the growth of a tumor.
Expanding the passageway for smooth flowing is needed in such cases, and for this purpose devices for pushing an elastic body which can expand by itself in the constricted passageway are proposed and used. The elastic body is called a stent, for example, a wire formed in a closed zigzag configuration, joined by a plurality of bends and wound cylindrically, as can be seen in EP 0177330.
Since each section of the stent of the above structure is formed by a plurality of connecting members linking section to each other to be used in practical use. Thus, when the stent is placed in a bent portion of the lumen, a space is formed between a bend of a first stent section and a corresponding bend of a second stent section. The space allows restenosis of passageways or ducts in the body.
To avoid the use of numerous connecting members, U.S. Pat. No. 4,733,665 discloses a graft which is formed by a tubular shaped member having first and second ends and a wall disposed between the first and second ends. The wall surface is formed by a plurality of intersecting elongate members, at least some of the elongate members intersecting with one another intermediate the first and second ends of the tubular shaped member. In the graft of this configuration, since a plurality of elongate members only intersect with each other, the elasticity of the graft is formed only in the first and second ends of the tubular shaped member and it is weak between the ends.